The causal relations among stressors, social support and illness will be examined in a longitudinal study. The primary purpose is to ascertain the intervening effect of social support between stressors (stressful life events) and illness (both physical and psychiatric disturbances). However, the design will allow us to examine the alternative models in which the stressors may serve as intervening variables or the illness may play a primary causal role in the occurrences of stressors and the erosion of social support. In our current project, a representative sample (N equals 1100) of adults from a tri-city area (Albany-Schenectady-Troy, which is also a Census SMSA area) were studied in order to construct reliable and valid measures of social support and to test a number of hypotheses regarding the relationships among stressors, social support and illness. The cross-sectional data yielded a number of reliable and valid scales of social support (e.g., instrumental support, expressive support, durability of a confidant and neighborhood and community satisfaction) and showed that these scales contributed significantly to the variation of psychiatric (especially depression) symptoms (as measured by the CES-D and Gurin scales). These relations held, even when sociodemographic and stressors were taken into account. The proposed study will conduct two follow-ups on the same respondents. The three-wave design provides a most rigorous analysis of the causal patterns among stressors, social support and illness. Also included in the design will be measures of history of illness, health help-seeking behavior, and a psychological factor (locus of control). For analyses, the generalized least squares with instrumental variables approach (GLS-IV) and the structural equation modelling approach will be utilized.